1. Field of the Invention
The present invention relates to a device for transmitting and receiving ultrasonic waves. More particularly, the present invention relates to, for example, an ultrasonic transceiver and a vehicle-surroundings obstruction sensor which are to be used in an obstruction detection system mounted in a vehicle bumper for sensing obstructions located around the vehicle.
2. Description of the Related Art
Ultrasonic transceiver sensors for sensing obstructions located around a vehicle have hitherto been known. More specifically, ultrasonic transceiver sensors are mounted in a bumper of a vehicle, and ultrasonic waves are transmitted from the rear portion or corners of the vehicle. Ultrasonic waves reflected from obstructions are received by the transceiver sensors, thereby detecting the obstructions. Within each ultrasonic sensor, an ultrasonic vibrator is built into a case, and a disc-shaped oscillation plane is also provided. By application of a voltage to the ultrasonic sensor, the ultrasonic vibrator undergoes oscillation by means of the piezoelectric effect, thus transmitting an ultrasonic signal. Upon receipt of the ultrasonic signal reflected from the obstruction, a piezoelectric element provided in the ultrasonic sensor produces a voltage by means of the reverse voltage effect.
Further, there have commonly been employed ultrasonic sensors provided in the front section of the vehicle for detecting obstructions located around the front section of a vehicle.
FIG. 8A is a cross-sectional view of a related-art ultrasonic transceiver sensor 80 when viewed from the side. FIG. 8B is a cross-sectional view of the same when viewed from the top. A known ultrasonic transceiver sensor has a piezoelectric transducer element provided therein. Further, the ultrasonic transceiver sensor comprises an ultrasonic sensor 81 for transmitting and receiving ultrasonic waves; a control board 82 for controlling the ultrasonic sensor 81; external input/output wiring 83 for connecting the control board 82 to an external ECU for vehicle use; and a case 84 for housing therein the ultrasonic sensor 81 and other elements. Particularly, the case 84 is provided with an opening section 85. The opening section 85 is formed so as to assume an oval-horn-shaped cross section for improving the directivity of ultrasonic waves transmitted from the ultrasonic sensor.
A rubber holder 86 is provided a round the ultrasonic sensor 81 such that the ultrasonic sensor 81 is secured and can undergo oscillation. A received-wave amplifier AMP 87 is mounted on the control board 82 for amplifying the signal received by the ultrasonic sensor 81.
Other related-art technologies are as follows: Japanese Patent Application Laid-Open No. 182571/1983 describes an obstruction sensor comprising an ultrasonic transmitter and an ultrasonic receiver that are provided separately and whose respective characteristics are changed. Japanese Patent Application Laid-Open No. 148975/1985 describes an ultrasonic sensor, in which an electronic component and elastic filler are provided in the base section of a horn. Japanese Utility Model Application Laid-Open No. 12686/1987 describes a vehicle rear monitor using a rear bumper as an ultrasonic block wall. Japanese Patent Application Laid-Open No. 284896/1997 describes an ultrasonic transceiver, in which the shape and thickness of a case for housing a piezoelectric transducer are controlled so as to provide directivity. Further, Japanese Patent Application Laid-Open No. 332817/1998 describes an ultrasonic sensor for preventing erroneous assembly, by means of rendering the longitudinal geometry of a housing of an ultrasonic vibrator different from that of the housing.
In a related-art ultrasonic transceiver, when a horn is formed into such a geometry as to provide directivity, ultrasonic wave are attenuated by the horn. Alternatively, the overall length of the ultrasonic transceiver becomes longer, and the horn section becomes prone to clogging with dirty snow.
Even when an attempt is made to control the geometry of a housing of a vibrator of the ultrasonic sensor so as to provide directivity, sufficient directivity is not achieved, the geometry of the housing or the geometry of a horn becomes complicated, or processes for forming the housing or the horn become complicated.
The present invention has been conceived to solve the aforementioned problems and provides an ultrasonic transceiver providing directivity by means of a simple construction.
The present invention is aimed at providing a sensor for detecting obstructions located around a vehicle, wherein the sensor has a detection area suitable for detecting obstructions located behind the vehicle.
The present invention provides a ultrasonic transceiver comprising:
a ultrasonic sensor provided with a transducer;
a case for housing the ultrasonic sensor therein; and
a resilient member to be interposed between the case and an ultrasonic sensor, wherein the surface of the case opposing a side surface of the ultrasonic sensor is tapered with respect to a surface of the ultrasonic sensor without involvement of the resilient member.
The present invention also provides a ultrasonic transceiver comprising:
a ultrasonic sensor provided with a transducer;
a case for housing the ultrasonic sensor therein;
a resilient member to be interposed between the case and an ultrasonic sensor; and
a tapered section which is formed in the case and opposes the side surface of the ultrasonic sensor exposed from the resilient member, wherein ultrasonic waves transmitted from the ultrasonic sensor are reflected from the tapered section and transmitted in substantially a forward direction of the ultrasonic sensor.
The present invention provides a vehicle-surroundings obstruction sensor comprising:
an ultrasonic transceiver including a case for housing a ultrasonic sensor having a transducer provided therein, a resilient member to be interposed between the case and an ultrasonic sensor, and a tapered section which is formed in the case and opposes the side surface of the ultrasonic sensor exposed from the resilient member; and
a determination section for determining whether or not obstructions are present, by means of a signal output from the ultrasonic transceiver; wherein
ultrasonic waves transmitted from the ultrasonic sensor are reflected from the tapered section and transmitted to the surroundings of the vehicle, so that the determination section detects obstructions located in the surroundings of the vehicle.
Preferably, an end section of the tapered section is flush with or higher than an end section of the side surface of the ultrasonic sensor.